MISRA.BASE.VIRTUAL.NOTVIRTUAL

Base class is used as both virtual and not virtual in inheritance hierarchy.

MISRA-C++ Rule 10-1-3 (required): An accessible base class shall not be both virtual and non-virtual in the same hierarchy.

Rationale

If a base class is both virtual and non-virtual in a multiple inheritance hierarchy then there will be at least two copies of the base class sub-object in the derived object. This may not be consistent with developer expectations.

Example

   class A {};

   class B1: public virtual A {};

   class B2: public virtual A {};

   class B3: public A {};

   class C: public B1, B2, B3 {}; // Non-compliant —
                                  // C has two A sub-objects